Why let your LHO overcall a major at the 1-level? Rather have them lead it if my hand is no trump oriented. I actually prefer 1nt is inv and 2nt a game force, but playing 6-10 it is best to win the race to 1nt when feasible.

No, bidding 3♦ on a weak 5-card suit is too risky. Doubling for takeout is also risky, because opener may leave it in and you aren't eager to defend 2♥X. If opener bids 2♠, you are poorly positioned. You could bid 3♣ and hope partner ...